Hi Janet,
In my almost two years in aikido and in Aikiweb, I have always found your post insightful and educational. I am sorry to hear that you are stopping your aikido training. I would probably do the same if I were in your shoes. I was wondering if you ever tried kiatsu to press your joints and improve flexibility and blood circulation. Here at our association, we have folks closing the age of 60 (may be even beyond) who are still active. I don't know if they have any conditions similar to yours.
I'm sure you will be missed at your dojo.